Apparatus for applying, tensioning and sealing a synthetic band around a package

ABSTRACT

Apparatus for applying, tensioning and sealing a synthetic band in a looped path around a package has a hold-down clamp upstream of the loop to keep the band under tension. Closing mechanism is provided where the band portions forming the loop overlap each other, in the form of a part that is horizontally reciprocable and in one position communicates with the guiding passage for the band about the loop, and in another position cooperates with a vertically reciprocable sealing block which carries a cutting element. After the hold-down clamp is released and the sealing block has returned to its starting position, the horizontally reciprocable part returns to the position in which the guiding passage is connected through; and during this movement, the cutting of the band is completed.

United States Patent van de Bilt Sept. 12, 1972 [54] APPARATUS FOR APPLYING,

TENSIONING AND SEALING A SYNTHETIC BAND AROUND A PACKAGE [72] Inventor: Pieter Arnoldus van de Bilt, Duinweg 24, Zeist, Netherlands 22 Filed: Dec.7, 1970 21 Appl. No.: 95,686

[30] Foreign Application Priority Data Dec. 10, 1969 Netherlands ..6918528 52 US. (:1. ..53/198 R, 100/17 51 Int. Cl. ..B65b 13/04 [58] Field Of Search .53/3, 198; 100/17, 29, 30

[56] References Cited UNITED STATES PATENTS 3,224,161 12/1965 Conti ..53/198 R 3,470,814 10/1969 Tschappu ..53/1.98 R 3,269,300 8/1966 Blllett et al. ..l0O/8 Primary Examiner-Theron E. Condon Assistant Examiner-Eugene F. Desmond Attorney-Young & Thompson [57] ABSTRACT Apparatus for applying, tensioning and sealing a synthetic band in a loopedpath around a package has a hold-down clamp upstream of the loop to keep the band under tension. Closing mechanism is provided where theband portions forming the loop overlap each other, in the form of a part that is horizontally reciprocable and in one position communicates with the guiding passage for the band about the loop, and in another position cooperates with a vertically reciprocable sealing block which carries a cutting element. After the hold-down clamp is released and the sealing block has returned to its starting position, the horizontally reciprocable part returns to the position in which the guiding passage is connected through; and during this movement, the cutting of the band is completed.

4 Claims, 10 Drawing Figures PATENTEDSEP 12 m2 SHEET 1 [IF 6 INVENTOR P/E TE? Ale/v04 pus MN 05 5/4 T BY 7 0 7 17M ATTORNEYS PATENTEDsEP 12 m2 3.690.090

' sum 2 or e 4 INVENTOR 1 /5 715 42/1 04 003 Wm 06 5/4 T BY *JWMJ ATTORNEY PATENTEDsEP 12 m2 SHEET 5 BF 6 INVENTOR ATTORNEYS APPARATUS FOR APPLYING, TENSIONING AND SEALING A SYNTHETIC BAND AROUND A PACKAGE The present invention relates to apparatus for applying, tensioning and sealing a synthetic band around a package, comprising a clamping means for holding the front end of the band, a device for tensioning the band around the package, a closing mechanism which connects the overlapping band parts to each other, a cutting device which severs the band loop from the stock, as well as means by which the tension in the band can be relieved before the cutting device has finished cutting through the band. Apparatus of this type is disclosed in British Pat. No. 1,033,526, which discloses a simple apparatus to be operated by hand, and which tries to provide a solution for the problem that when the synthetic band is being cut off under tension, said band will split due to the molecular orientation. The result of said split is band ends which are difficult to handle.

In this known apparatus, it is suggested as a solution of this problem to relieve the tension in the band just before the cutting of the band is carried out and/or has been completed. This takes place in that the handoperated knife will unlock the device which has tensioned the band. But upon fast operation by hand such a mechanism does not operate fast enough, and fraying of the band ends will occur by splitting. With an automatically operating machine this is absolutely unacceptable, as a proper guiding of the front end of the band through a guide frame is then not possible and the end clamp customary with such automatic machines cannot hold the band end properly.

The object of the present invention is to overcome the difficulties recited above.

Briefly, this object is achieved in accordance with the invention by apparatus comprising a band guide frame having a guiding passage by which a band can be guided about to a looped path that terminates in an end clamp. Before the beginning of the looped part of the path and after the means for feeding, retracting and tensioning the band, a hold-down clamp is provided which keeps the band under tension. Just before the end clamp, where the band portions forming the loop overlap each other, the sealing mechanism comprises a member which can be moved forward and backward in a horizontal direction, which member in one position connects through the guiding passage and another position co-operates with a sealing block which can be moved up and down and which carries a cutting element, the parts of which element can be controlled by means of switches and the like so that after closing the seal the sealing block will move down again and will release the hold-down clamp; and after the sealing block has returned to its starting position, the horizontally movable part will return to the position in which the guiding passage has been connected through, during which movement the cutting through will take place. Thus, a sufficient lapse of time is achieved for expanding the band in order to ensure that said band may loosen itself from the hold-down clamp and may expand and, thereby, also it is ensured that the cut off front end of the band has, on no account, been split and, thereby, might obstruct further feeding.

It is also useful to give the cutting element of the cutting device a cutting edge perpendicular to the plane of the band and to move said cutting edge in the direction of the plane of the band, so that the cut will act on the small side of the band. Thus, a compact structure of the cutting device is achieved without splitting. This may still occur with a knife having a sheared cutting edge, resulting from lateral deflection of the fibers.

The mounting of the sealing mechanism in a horizontally and vertically movable member permits a simple construction, which allows easy disassembly, eg for cleaning purposes or replacement of the knife. To that end, in accordance with the invention the frame of the machine just below the lower part of the band guide frame has a rectangular guiding passage transversely of said band guide frame and open at the top, in which passage a hollow rectangular block is located having vertical side walls and end walls and which can be removed from the top. This block can perform in the guiding passage a limited forward and return stroke with two end positions. Within said block is guided the vertically movable sealing block, said block being provided at one end with a cover plate having two guide slots for the band. The said slots are open toward one side and located immediately above each other and lie in one position of the block in the extension of the guide slots of the band guide frame. At the other end a cover plate is provided, the under-face of which has a profiled part which cooperates with the sealing block for closing a seal positioned in said block and which part is flanked on both sides by slidable parts on the upper edges of the block, said slidable parts being guided in passages open at the top, with band guide slots at the location of the cover plate, said parts being held against a stop by a spring in the direction of the first cover plate and being connected to the first cover plate by a cross pin in a transverse slot of said first cover plate. The slot is open at the top, and with slots of lesser depth in said parts, said cross pin acting in concert with ascending sides on the upper edges of the passage side walls, so that after a certain movement of the block, unlocking of the parts guided thereon takes place by the fact that the cross pin will pass out of the slots of lesser depth. These parts also have an escape slot open at the top just before the second cover plate and one of these parts has a cutting knife at the location of said escape slot, said cutting knife being located only at the level of the lowest guide slot for the band.

This construction makes it possible, after the removal of the work table plates on which rest the packages to be bound, to lift said parts up out of the guiding passage.

The invention will now be described more in detail with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary perspective view of a portion of apparatus lying just below a work table (not shown) in accordance with the invention. The Figure is a diagrammatic representation and parts which are not important or which are generally known have been omitted;

FIG. 2 shows a portion of the mechanism of FIG. I seen from above at an angle;

FIG. 3 is a sectional view along the plane of the guiding frame;

FIGS. 4a, b and c show the parts of FIG. 2 disassembled;

FIGS. and 6 show two different working positions of the mechanism shown in FIGS. 2, 3 and 4;

FIG. 7 is a pneumatic circuit diagram of the complete device; and

FIG. 8 is the corresponding electrical diagram.

FIG. 1 shows a wire guide frame 1, of which frame only a part of the horizontal part and a part of a vertical leg are shown. In reality this is, of course, a closed rectangle. Band guides 2 are located in the horizontal and vertical parts of said guide frame 1. Guides 2 are slidable transversely of the plane of said frame and may be deflected from the position shown in the drawing by pneumatic cylinders (not shown) and in which guides a U-shaped band guiding passage 3 is provided. The guidemeans 2a cover an upper guide slot 3a, while, in addition, a lower guide slot 4 can be seen. Slot 4 lies in line with the feed mechanism (not shown), which is positioned at the right side of said slot in the frame of the machine. Also the means for withdrawing the band and tensioning the same can be located there.

A movable packing block 5 and a fixed part 6 are positioned in the path of the band, between which parts the band can be gripped in order to keep said band tensioned. The movable packing block 5 may be moved by means of an eccentric 7 on a shaft 8 with lever 9, which is connected to a cylinder 164.

The frame of the device has, about in the middle below the work table and transversely of the plane of the band guide frame 1, a guide passage 14 open at the top and formed by two vertical plates 10 and 11 having horizontal ledges 12 and 13.

A block 15 is slidable in the guiding passage 14. Block 15 may be moved forward and backward by means of a cylinder (not shown) connected at 16. A cross plate 17 functions as a stop. The block 15 is shown more in detail in FIG. 2 and in FIGS. 4a, b and c. Said block comprises a main body 18 and two side pieces 19 and 20, which are positioned in rectangular recesses in the upper edges of the main body 18 (FIG. 3).

The sealing block 21 is guided in the interior of the block 15. Block 21 can be moved up and down by means of the cylinder 137 which is hinged to block 21 through the rod 22. The block 15 has two cover plates 23 and 24 on the upper side. The cover plate 23 is provided with slots 25 and 26, as shown in FIG. 4b, which plate may bridge across the guiding passage for the band at the location of the interruption formed by the passage 14.

7 Plate 23 also has a vertical transverse slot 27 therein open at the top.

The cover plate 24 has recesses 28 on its underside, so arranged that plate 24 in co-operation with the toothed head of the sealing block 21 is able to fold a U- shaped preformed seal over the band to provide said seal with indentations in order to retain the band pieces.

At the right side of FIG. 3 the part is slidably supported on the block 15. Said part 20 is held against the stop 17 by a spring 30, is provided with a recess 31 and is connected for common movement by means of a cross pin 32 engaging in the recess 27 of the cover plate 23 and the slot 31 and, thereby, connecting the part 20 to the block 15. The part 20 carries a knife 33 the vertical cutting edge of which acts only in the plane of the slot 34.

The side walls 10 and 11 have upwardly inclined sides 35 which coact with the locking pin 32. When the block 15 is moved to the right as a whole, the part 20 will move along with the knife 33 until the part 20 will be unlocked because the pin 32 strikes the upwardly inclined side 35, part 20 will then be pulled backward by the spring 30. However, the band passing through the slot 34 has then been cut through and has been released through the opening 36.

The part 19 is supported at the left top edge in a rectangular recess in the block 15. The packing block 37 is positioned with the end clamp 38 laterally of said part 19, said end clamp being operated by means of the cylinder 212 which is attached to the plate 10. Packing block 37 has a slot 39 in which the end of the band is retained, as well as a slot 40 which forms the through connection for the slot 4. The block 37 moves along with the part 19 because it is attached to part 19 by screws 41. This is necessary in order to permit the band to escape from the slots 39 and 40 and the clamp 38 after sealing.

FIG. 5 illustrates one end position of the block 15, in which the seal is completed. This position is also shown in FIG. 1.

FIG. 6 illustrates the other end position, in which the parts 19 and 20 are unlocked and in which the plate 23 with its guide slots is in line with the band guide slots of the guide frame. When the block is moved back out of this latter end position, then the locking pin 32 will automatically return into the slots 31 and 42 of the parts 20 and 19 respectively. The slot 42 in the part 19 is slightly longer, so that when the block 15 is being moved, the end clamp will move somewhat later than the knife 33. This is necessary in order that no other side forces occur on the band during the cutting operation.

In accordance with the invention, the control of hold-down clamp 5, block 15, sealing block 21 and end clamp 38 takes place in a certain order. According to this sequence the clamp 38 is closed at the end of the in-feed of the band. After the guide frame has been opened in response to a signal, the band has been retracted, wound over the package and subsequently been tightened around the package, the clamp 5 will come into action in order to maintain the tension created in the band during the closing procedure.

During this period, the block 15 is in the position shown in FIG. 6 but then the block moves to the position shown in FIGS. 1 and 5. The sealing block 21 provided with a seal moves subsequently upward and the seal is closed around the overlapping band pieces. As soon as an appropriate measuring apparatus has given the signal that the closing has been completed, the sealing block 21 will move down again. The signal by which the sealing block is sent down is used in addition for releasing the clamp 5 and only when the sealing block has been returned to its starting position is a signal given by means of which the block 15 is moved again to the starting position (shown in FIG. 6). The band, which has become tensionless in the meantime, i.e. tensionless at the part to be cut off which extends to the supply, is now cut off by the knife 33 and the band loop obtained can then pass through the escape opening 36,

43. When this has taken place, the parts 19 and 20 will be unlocked and will move backward, while the block moves on to the position indicated in FIG. 6, in which the guide slots 3 and 4 in the lowest part of the guide frame 1 are closed and the band can be fed in again.

The band will thus have enough time to become tensionless, which takes a certain time with even an automatic machine of the present invention, albeit a very short time.

In the following description, the operation of a machine according to the invention will be elucidated with reference to FIGS. 7 and 8. It should be noted that the machine itself, as a whole, is not shown, as machines of this kind and the apparatus indicated in the diagrams are disclosed in many publications.

The circuit diagrams of FIGS. 7 and 8, of which FIG. 7 illustrates the pneumatic diagram and FIG. 8 the electrical diagram, are described as follows.

In FIG. 7, the compressed air coming from a compressed air source (not shown) is supplied through a pipe 100 and arrives in the main feed pipe 104, through a filter 101, a pressure regulator 102 and a lubricating element 103, under a pressure of e.g. 6.3 kg per cm A pressure switch 105 is connected to pipe 100 by means of a branch pipe 106 between the pressure regulator 102 and the lubricating element 103. The advantage of pressure press-re switch 105 will become apparent later.

The compressed air may act on the rod side of a cylinder 117 through a pipe 110 branched from pipe 104, a pressure regulator 111 and an electromagnetically operated valve 113. Cylinder 117 serves for returning the re-tension device. The electromagnetically operated valve 113 acts so that when the magnet coil 114 is energized, the compressed air will act on the,

rod side of the cylinder 117, while when the magnet coil 114 is not energized, the valve 113 will be held by a spring 115 in a position in which the rod side of the cylinder 117 is in communication with the atmosphere.

The upper end of cylinder 117 is connected to the main feed pipe 104 by means of a pipe 124, an electromagnetically operated valve 121 and a pipe 120. Valve 121 acts so that when the magnet coil 122 is energized, the compressed air on the upper end of the cylinder 117 may act, while, when the magnet coil 122 is not energized, the valve 121 will be held by the spring 123 in a position in which the upper end of the cylinder 117 is in communication with the atmosphere.

The main feed pipe 104 can be connected to the lower end of a cylinder 135 by means of a branch 130, a pneumatically operated valve 131 and a pipe 134. Cylinder 135 controls the in-feed of the sealing band. The valve 131 acts so that when the pressure in the steering port 133 is higher than in the steering port 132, the lower end of the cylinder 135 will be connected to the main feed pipe 104, while in the other case the lower end will be in communication with the atmosphere. In that case the pipe 130 will be connected to a pipe 136 opening into the lower end of a cylinder 137 operating the closing template of the seal. The lower end of the cylinder 137 is in communication with the atmosphere in the other position of the valve 131 (the pressure in steering port 133 being higher than the pressure in steering port 132).

The main feed pipe 104 is connected to one end of a cylinder by means of a branch pipe 150, a pneumatically operated valve 151 and a pipe 154. Cylinder 155 operates the sealing block. This connection is made when the air pressure in the steering port 152 of the valve 151 is higher than in the steering port 153. At the same time, the rod side of the cylinder 155 is in communication with the atmosphere through the pipe and the valve 151. The pipe 160 has two branch pipes 163 and 161, which are connected to the rod side of a cylinder 164, operating the middle clamp, and to the rod side of a cylinder 162 respectively. Cylinder 162 operates the sealing band cutting-off mechanism and form mechanism. The pipe 154 is also provided with two branch pipes 156 and 159, pipe 156 being connected to the rod side of the cylinder 135 by means of an alternating relay 157 and a pipe 158. Cylinder 135 controls the in-feed of the sealing band. When the air pressure in the steering port 153 is higher than in the steering port 152, the pipe 154 will be in communication with the atmosphere and the pipe 160 will be connected to the main feed pipe 104 and vice versa. The air pressure in the steering port 153 is regulated by a sequential valve 166 and a pipe 165, which forms a branch pipe of the pipe 124.

The branch pipe 159 can be connected to the steering port 145 of a valve 146 by a hand-operated valve 141. The valve 141 acts-so that when no hand operation is carried out, the spring 143 will hold the valve 141 in a position in which the pipe 159 is not connected to the steering port 145, port 145 being in this case in communication with the atmosphere. When the valve 141 is reversed by hand, then pipe 159 will be connected to steering port 145, and the spring 143 will cause the valve 141 to return automatically to its starting position when the operation by hand has stopped. The valve 141 serves as a resetting device.

A pipe branched from the main feed pipe 104 may be connected by means of a pneumatically operated valve 181, either to a pipe 184 or to a pipe 191, said pipe 191 being in communication with the atmosphere when the pipe 184 is connected to the pipe 180 and vice versa. The pipe 184 is connected to the lower end of the cylinder 162 by means of a branch pipe 190. The pipe 184 can also be connected to one end of a cylinder 189 by means of a mechanically operated valve 185 and pipe 188, said cylinder 189 operating the in-feed of the preformed closure. The mechanical operation of the valve 185 takes place by means of the cutting-off lever of the sealing band, i.e. in a manner such that when said lever isin its highest position, the pipe 184 will be connected to said one end of the cylinder 189, while in the other case the spring 187 will press the valve 185 into a position in which said one end of the cylinder 189 is in communication with the atmosphere.

The pipe 191 is connected to the upper'ends of a number of cylinders 192, which serve for opening the band guide frame. From these cylinder ends extends a branch 193, which is connected to the right end of a cylinder 199 by means of an alternating relay 197 and a pipe 198. Cylinder 199 operates the band return pawl. A pressure spring 200 is provided in the left end of said cylinder 199, between thepiston and the cylinder. Two pipes 194 andv 195branchedloff from the pipe 193 are connected to the left end of the cylinder 189 and the upper end of cylinder 196 respectively, said cylinder 196 operating the band return hold-down roller.

The steering port 182 of the valve 181 is connected to the main feed pipe 104 by means of a pipe 174, an electromagnetically operated valve 171 and a pipe 170. The valve 171 acts so that when the electro-magnet 172 of said valve 171 is not energized, the valve 171 will be held by a spring 173 is a position in which the pipe 174 is in communication with the atmosphere, and in the other case the pipe 170 is connected to the pipe 174.

Finally, the main feed pipe 104 is connected to a pipe 210 by means of valve 146, said pipe 210 opening into the steering port 133 of the pneumatically operated valve 131. A pipe 213 branched from the pipe 210 is in communication with the atmosphere by means of an electromagnetically operated valve 214, a pipe 217, a throttle opening 219 and the opening 44. Said opening 44 is located in the bend of the band guide frame, as described in copending application Ser. No. 868,370, filed Oct. 22, 1969. A branch pipe 218 is located between the throttle opening 219 and the opening 44, said branch pipe 218 being connected to the steering port 147 of the valve 146. The pipe 221 is connected to the steering port 183 of the pneumatically operated valve 181 by means of a pipe 220 and connected to the lower end of a cylinder 223 by means of the pipe 222, said cylinder 223 operating the band in-feed hold-down roller. The electromagnetically operated valve 214 acts so that when the electromagnet 215 is energized, the pipe 217 is connected to the pipe 213, while when said electromagnet 215 is not energized, the spring 216 will bring the valve 214 into a position in which the pipe 217 is in communication with the atmosphere.

The pipe 210 is connected to the lower end of a cylinder 212 by means of a branch pipe 211, said cylinder 212 operating the end clamp. Another pipe 229, branched from the pipe 210 connects the pipe 210 to the rod side of the cylinder 196. The pipe 210 is connected in addition to the lower end of the cylinder 164 by means of the pipe 230 and said pipe 210 is also connected to the rod side of the cylinder 137 by means of the pipes 230 and 231. Finally, the pipe 210 is connected to the steering port 152 of the pneumatically operated valve 151 by means of the pipe 224, the mechanically operated valve 225 and the pipe 228. The mechanical operation 226 of the valve 225 takes place by means of the seal closing lever, in a manner such that in the lowest position of said seal closing lever, the pipe 224 will be connected to the pipe 228, and such that when the seal closing lever has moved from its lowest position, the spring 227 will bring the valve into a position in which the pipe 228 is in communication with the atmosphere.

The main feed pipe 104 can also be connected to the pipe 232 by means of the pneumatically operated valve 146. Said pipe 232 is connected to the rod side of the cylinder 212 by means of a pipe 233, to the rod side of the cylinder 223 by means of the pipe 234, to the right end of the cylinder 199 by means of the pipe 235 and the alternating relay 197, to the rod side of the cylinder 135 by means of the pipe 237, 238 and the alternating relay 157, as well as to a pressure switch 236 and can be connected to the steering port 132 of the pneumatically operated valve 131 by means of the pipe 237, the mechanically operated valve 239 and the pipe 242. The valve 239 is mechanically operated at reference numeral 240 by means of the sealing block, in a manner such that in the advanced position of said sealing block, the pipe 237 will be connected to the pipe 242 and in the starting position of the sealing block, the spring 241 will act in a manner such that the valve 239 will take up a position in which the pipe 242 is in communication with the atmosphere.

FIG. 8 is the electrical diagram of the equipment. A three-phase electromotor 250 is connected to the electrical supply lines by means of a main switch 252, fuses 253 and relay contacts 254a.

The electric elements, which operate the machine in cooperation with the pneumatic elements shown in FIG. 3 and with mechanical means, are fed by means of a transformer 255, the primary winding of which is connected to two of the three supply lines of the electromotor 250.

The secondary winding of the transformer 255 is connected to two voltage terminals 256 and 257. The electric circuit between said terminals 256 and 257 can be closed by means of safety fuse 258 and a number of circuits connected thereto.

The first circuit comprises a pressure switch 261, a conductor 262 and a control lamp 263 which burns only when the air pressure has fallen below a certain value. The second circuit consists of a pressure switch 266, a conductor 267, and a control lamp 268 indicating that there is sufficient air pressure. The switches 261 and 266 are mechanically connected in a manner such that when one switch is closed, the other will be open and vice versa. Said switches 261 and 266 are operated by the pressure switch 105 (FIG. 3).

A third circuit consists of pressure switch 266, sealing block switch 270, sealing band storage switch 271, safety switch 272, pressure switch 273 and the electromagnet 215 of the valve 214.

The fourth circuit consists of the switches 266, 270, 271, 272, 273, as well as the wire guide switch 274, relay contact 275, and the electromagnet of the time relay 276, whose coil is connected in parallel to the time relay contact 276a and the coil 254 of the motor relay. This last circuit is closed during the in-feed of the band. During the return of the band, the circuit is formed by 266, 270, 271, 272, 277, 278, 275b, time relay contact 276a and motor relay 254. The coil of relay 275 is connected in parallel through 275b, 276a and 254. During the re-tension operation, the circuit 270, 271, 272, 277, 278 and 284 is closed as well as the electromagnet 122 of the valve 121.

During the start of the winding process the circuit consists of 266, 270, 271, 272, 277, 288, starting switch 286, electromagnet 172 of valve 171. An electromagnetic counter 289 is positioned in parallel with coil 172. This last circuit consists of switches 266 and 290, as well as electromagnet 114 of valve 113 and serves for returning the re-tension device.

FIGS. 7 and 8 show the valves, cylinders and switches in their position during the period in which the in-feed of the band takes place, while, in addition, the cutting off of a seal from a sealing band stock, the bending of a U shape of said seal and the placing of said seal into the sealing block have already taken place.

As soon as the band is retained in the end clamp 38 and the air outflow opening 44 in one of the bends of the band guide frame 1 is closed, the air pressure in the lowest steering port 147 of the valve 146 will increase, as a result of which valve 146 will be reversed. By this reversal the rod side of the cylinder 212 is connected to the pressure of the feed pipe 104, as a result of which the end clamp 38 is closed. At the same time, pressure air is supplied to the cylinder 223, whereby the band infeed is stopped and the rod side of the cylinder 137 is vented, said cylinder being connected to the sealing block, while, in addition, the bottom side of the cylinder 164 of the hold-down clamp 5 is vented, the rod side of a cylinder 196 operating the band return device, as well as the upper steering ports 183 of valve 181, 152 of valve 151 and 133 of valve 131. Moreover, air is supplied to cylinder 199 acting on a band return pawl situated near the storage roller (not shown), said pawl ensuring that during the retracting and re-tensioning of the band this band cannot return and form loose loops on the storage roller. Moreover, air is supplied to the pressure switch 236, whereby the band-conveying motor becomes tensionless.

In order to effect winding, the switch 286 (FIG. 8) is closed, as a result of which the electromagnet 172 is excited by means of the closed switches 270, 271, 272, 277 and 288, whereby the valve 171 will reverse and steering air will be supplied to the lowest steering port 182 of the valve 181, as a result of which said valve will reverse.

The consequence of this reversal is that pressure air is supplied to the cylinder 192 through the pipe 191, whereby the band guide frame 1 is opened. Moreover, pressure air is supplied to the rod side of the cylinder 189 so that the tongue is withdrawn by means of which the cut-off seal was fed in. Furthermore, the lower end of cylinder 162 of the sealing band cutting-off device is vented and pressure air is supplied to the upper end of the cylinder 196 in order to make the retracting device withdraw the band. By opening the band guide frame 1, also the switch 274, 278 is reversed, as a result of which the band conveying motor is energized again by means of switches 270, 271, 272 and the contacts now closed of switches 277, 278 and 275 (275b closes and 275a opens).

The band is thus pulled around the package until a certain initial tension is achieved and the switch 284 reverses because of the tension of the band, as a result of which the switch 290 will open and the energizing of the coil 114 is relieved, whereby the rod side of the retension cylinder 117 is vented. By closing the switch 284 the coil 122 is energized whereby the valve 122 supplies air pressure to the upper end of the cylinder 117, as a result of which the re-tension device will come into action.

As soon as the air pressure in the cylinder 117 has reached a value which is larger than the set value of the sequential valve 166, then valve 166 passes air to the lowest steering port 153 of the valve 151. Valve 151 will reverse, whereby the sealing block connected to the cylinder 155 is pulled forward in order to bring the seal under the tensioned band. At the same time, the clamp 5 closes, because pressure air is supplied to the cylinder 164 so that the tension in the band is maintained and the piston rod of the cylinder 162 is moved down while operating the device for cutting off the sealing band.

By the forward motion of the block 15, the switch 270 has been opened, as a result of which the band conveying motor is de-energized again, as well as the coil 122 of the valve 121. 1

The re-tension cylinder 117 can now vent again, so that the tension in the band and, therewith, on the switch 284 and 290 is relieved. As a result thereof, the coil 114 is energized again and the valve 113 is reversed, whereby now air is transmitted to the rod side of the cylinder 117 under pressure reduced by the device 111, so that the re-tension device is returned to the starting position. When the block 15 reaches its advanced position, the valve 239 will be mechanically operated by electromagnet 240 and pressure air will be applied to the lowest steering port 132 of valve 131. Valve 131 will reverse, whereby the lower end of the cylinder 135 will be vented. Cylinder 135 operates the sealing band feed mechanism, and the sealing band feed clamp will return freely.

The cylinder 137 receives pressure air, whereby the sealing block 21 with the sealing jaw 29 will rise and the seal will be closed. As soon as the air pressure in the cylinder 137 has reached a larger value than the set value of the sequential valve 139 connected to the pressure supply pipe 136 by means of the pipe 138, then valve 139 will pass air to the upper steering port of valve 146, so that valve 146 will return to the position as shown in the drawing. The cylinder 212 will return to its starting position, the end clamp 38 will open and the cylinder 223 of the band return mechanism will continue to act with little force on the band, while the pressure switch 236 becomes pressureless. Cylinder 164 of the hold-down clamp 5 will receive pressure at its lower end, whereby clamp 5 will open because the working surface at the underside is larger than at the rod side of the piston.

By opening the clamp 5, the tension in the band disappears. By the fact that the steering port 133 of valve 131 receives pressure air, valve 131 will return to the position shown in the drawing. As a result thereof, the cylinder 137 will return to the starting position, while simultaneously the cylinder 135 of the sealing band feeding device will be supplied again with air. The piston of cylinder 135 will then move upward, which is possible by virtue of the reversal of valve 146, whereby the rod side had become pressureless, which means that a sealing band is again fed in.

Should there be an insufficient amount of sealing band, then the sealing band feed mechanism will travel a greater distance, whereupon it will open the switch 271, as a result of which the machine will stop.

When reaching the lowest position of the sealing block 21, the valve 225 will be mechanically operated by electromagnet 226, whereby steering air is admitted to the steering port 152 of valve 151. Valve 151 will return to the position shown, so that the left end of cylinder 155 moving the block 15 will be repressurized and the rod side of said cylinder will be vented, so that the block 15 can be pressed back again. As a result thereof, first the band, which has already become -tensionless before, is cut off between the closure and the band supply, whereupon the band guide, situated at the left side of the :plate 24"andfthe end clamp, situated at the other side thereof, will move farther backward simultaneously with the block 15 in order to free the complete winding. Thereafter, the parts 19 and 20 are unlocked and the block 15 moves on alone in the position in which plate 23 comprising slots 25 and 26 finishes the guiding path for the band in the band guide frame again.

As soon as the block 15 has fully returned, the switch 272 will be closed, as a result of which the coil 215 of valve 214 is energized, whereby the valve 181 is reversed by pressure air supply to the upper steering port 183.

The cylinder 192 of the band guide frame will then be vented, so that said frame will close under spring pressure and the piston of cylinder 223 is moved upward for operation of the band feeding elements, whereby the band is clamped against a feed roller. At the same time, by means of the cylinder 196, the band return mechanism is moved away from the band and the cylinder 199 disengages the band return pawl. The cylinder 162 provides the cutting off from a seal and the preform process. As soon as the piston of the cylinder 162 has reached its highest position, the valve 185 is reversed by electromagnet 186, as a result of which the feed mechanism operated by the cylinder 189 will place the preformed seal into the block 21. In addition, by reversing the switch 274 (by means of the band guide frame) the band conveying motor is energized again, whereby a band is fed in again and the cycle described may repeat itself.

In view of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described and illustrated in connection with a preferred embodiment, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

What is claimed is:

1. ln apparatus for applying, tensioning and sealing a synthetic band around a package, comprising means for feeding theband from a supply of the band, clamping means for holding the forward end of the band, means for retracting the band and for tensioning the band around the package, closing means to connect overlapping portions of the band to each other, cutting means to sever the looped band from said supply of the band, and means to relieve the tension of the band before cutting of the band is completed; the improvement comprising a band guide frame having a guiding passage through which the band is guided about a looped path, a hold-down clamp for the band to maintain the band under tension, said hold-down clamp being disposed between said looped path and said means for feeding, retracting and tensioning the band,

whigh in one positign provides connection with San gui mg passage an in ano er position coacts with a vertically reciprocable sealing block carrying said cutting means, and means for moving said sealing block downwardly after formation of a seal and for raising said hold-down clamp and for returning said horizontally reciprocable portion to said one position after said sealing block has reached its lower position and for completing the cutting through of said band.

2. Apparatus as claimed in claim 1, said cutting means cutting perpendicular to the plane of the band, and means mounting said cutting means for movement in the direction of the band surface.

3. Apparatus as claimed in claim 1, said frame defin ing a rectangular band guiding passage transversely to said band guide frame and open at the top, a hollow rectangular block disposed in said rectangular passage and having vertical side walls and end walls, said block being removable from above, means mounting said block in said rectangular passage for limited horizontal reciprocal movement, a sealing block in said rectangular block, said rectangular block having cover plate means comprising at one end a first cover plate having two vertically superposed horizontal guide slots forthe band, said slots in one position of said rectangular block being in line with guide slots of the band guide frame, said cover plate means comprising at the other end of said rectangular block a second cover plate whose undersurface is profiled to cooperate with said sealing block for closing a seal positioned in said rectangular block, said profiled undersurface being flanked on both sides by slidable parts on the upper edges of said rectangular block, said slidable parts being guided in passages open at the top and having band guide slots adjacent said cover plate means, a spring holding said slidable parts against a stop in the direction of said first cover plate, a cross pin connecting said slidable parts with said first cover plate in a transverse slot of said first cover plate which is open at the top, said cross pin cooperating with upright sides on the upper edges of the side walls of said rectangular passage so that after movement of said rectangular block, unlocking of the parts guided thereon takes place by the cross pin passing out of the last-named slot, said slidable parts having an escape slot open at the top just before said second cover plate, one of said slidable parts having a cutting knife at the location of said escape slot, said cutting knife being disposed at the level of the lowest guide slot for the band.

4. Apparatus as claimed in claim 3, said clamping means being disposed in the other of said slidable parts. 

1. In apparatus for applying, tensioning and sealing a synthetic band around a package, comprising means for feeding the band from a supply of the band, clamping means for holding the forward end of the band, means for retracting the band and for tensioning the band around the package, closing means to connect overlapping portions of the band to each other, cutting means to sever the looped band from said supply of the band, and means to relieve the tension of the band before cutting of the band is completed; the improvement comprising a band guide frame having a guiding passage through which the band is guided about a looped path, a hold-down clamp for the band to maintain the band under tension, said hold-down clamp being disposed between said looped path and said means for feeding, retracting and tensioning the band, closing means disposed in advance of said end clamping means with respect to the direction of travel of the band and disposed adjacent a portion of said path in which portions of the band overlap each other, said closing means having a horizontally reciprocable portion which in one position provides connection with said guiding passage and in another position coacts with a vertically reciprocable sealing block carrying said cutting means, and means for moving said sealing block downwardly after formation of a seal and for raising said hold-down clamp and for returning said horizontally reciprocable portion to said one position after said sealing block has reached its lower position and for completing the cutting through of said band.
 2. Apparatus as claimed in claim 1, said cutting means cutting perpendicular to the plane of the band, and means mounting said cutting means for movement in the direction of the band surface.
 3. Apparatus as claimed in claim 1, said frame defining a rectangular band guiding passage transversely to said band guide frame and open at the top, a hollow rectangular block disposed in said rectangular passage and having vertical side walls and end walls, said block being removable from above, means mounting said block in said rectangular passage for limited horizontal reciprocal movement, a sealing block in said rectangular block, said rectangular block having cover plate means comprising at one end a first cover plate having two vertically superposed horizontal guide slots for the band, said slots in one position of said rectangular block being in line with guide slots of the band guide frame, said cover plate means comprising at the other end of said rectangular block a second cover plate whose undersurface is profiled to cooperate with said sealing block for closing a seal positioned in said rectangular block, said profiled undersurface being flanked on both sides by slidable parts on the upper edges of said rectangular block, said slidable parts being guided in passages open at the top and having band guide slots adjacent said cover plate means, a spring holding said slidable parts against a stop in the direction of said first cover plate, a cross pin connecting said slidabLe parts with said first cover plate in a transverse slot of said first cover plate which is open at the top, said cross pin cooperating with upright sides on the upper edges of the side walls of said rectangular passage so that after movement of said rectangular block, unlocking of the parts guided thereon takes place by the cross pin passing out of the last-named slot, said slidable parts having an escape slot open at the top just before said second cover plate, one of said slidable parts having a cutting knife at the location of said escape slot, said cutting knife being disposed at the level of the lowest guide slot for the band.
 4. Apparatus as claimed in claim 3, said clamping means being disposed in the other of said slidable parts. 